Progressive Metal

Progressive metal is a subgenre of heavy metal, which blends the powerful, guitar-driven sound of metal with the complex compositional structures, odd time signatures, and intricate instrumental playing of progressive rock.
Progressive metal is guitar-driven and often features varying (and sometimes sudden) changes in time signatures. The genre is also known for lending itself to complex and extended guitar solos. Consequently, progressive metal songs can become relatively long. Read more on Last.fm.